Learning from Architects

From dog–houses to skyscrapers, the discipline of the building architect has long been a rich source of metaphor for system architects. I don't disagree, indeed in one of my contributions to the 97 Things Every Software Architect Should Know I recommended that software architects should learn from architects of buildings. So, you can imagine that my eye was caught by Matthew Frederick's 101 Things I Learned in Architecture School. This small book contains the eponymous count of hints, tips and tricks from a qualified architect to architecture students.

This is a good resource for those of us who would learn from architects of buildings, as it is advice to would–practitioners from a practitioner and as such relates to what building architects actually do, rather than what someone who isn't a practitioner thinks they must, surely, do. This latter is a common failure mode of software professionals seeking inspiration from other disciplines—all the way back to the very first Software Engineering conferences of the late 1960's, in which an hallucinatory notion of what "engineers" do was foisted upon us. But I digress.

Some of the 101 are very low level and very specific (eg Number 90 "Roll your drawings for transport or storage with the image side facing out"), others are much broader and seem to me to have relevance for any sort of design work.

Number 15 tells us that "A parti is the central idea or concept of a building." Wikipedia tells us that parti is from the French prendre parti "to make a decision". The parti captures, presents and summarises the highest level decision that has been made about the organising principle of an entire building or building project, and examples are given where the parti expresses all that in one, highly abstract, diagram.

A parti sounds to me a lot like a system metaphor.

Number 100 tells us that the parti should have a name, such as "half–eaten donut" or "meeting of strangers". Could the nominal (or de facto [*]) architect of the system that you are working on draw such a diagram? Would it tell anyone anything if they did? Could they name the parti, the very highest level design decision from which the rest of the system design flows?

Number 28 tells us that a good designer isn't afraid to throw away a good idea. Notice: a good idea. An idea can be good and not fit with the parti, in which case it has no place in the design. We are advised to "save [...] good but ill–fitting ideas for another time and project—and with the knowledge that they might not work then, either." When was the last time you (or your team) threw out a good idea?

Number 46 tells us to "Create architectural richness through informed simplicity or an interaction of simples rather than through unnecessarily busy agglomerations". Frederick warns particularly against "busying up a project with doodads because it is boring without them; agglomerating many unrelated elements without concern for their unity because they are interesting in themselves." What interesting doodads does your current project have?

One reason to follow the guidance of Number 46 is given in Number 51, which observes that "Beauty is due more to the harmonious relationships among the elements of a composition than to the elements themselves". One achieves this beauty through a design process, or system.

Number 77 cautions that "No design system is or should be perfect. Designers are often hampered by a well–intentioned by erroneous belief that a good design solution is perfectly systematic [...] but nonconforming oddities can be enriching, humanising aspects of your project." 77 also observes that "exceptions to the rule are often more interesting that the rules themselves."

Number 81 notes that "Properly gaining control of the design process tends to feel like one is losing control of the design process" 81 advises that the designer should "accept uncertainty. Recognise as normal the feeling of lostness that attends to much of the process. Don't seek to relieve your anxiety by marrying yourself prematurely to a design solution; design divorces are never pretty" No, they never are.

Number 99 can help. It says "Just do something. [...] don't wait for clarity to arrive before beginning to draw. Drawing is not simply a way of depicting a design solution; it is itself a way of learning about the problem you are trying to solve." I think that much the same can be said for coding. Are the design procedures in your team aligned with these principles?

[*] Even the most self–organised, most cross–functional, most Agile, most collectively–code–owning software development team will have one individual who knows most about (and likely has most influence over) the architecture of the system. You can pretend otherwise, or you can take advantage of it.

Bridging the Communication Gap

Call it automated acceptance testing, functional test driven development, checked examples or what you will—the use of automatic validation is one of the most effective tools in the Agile developer's kit.

It's a large and involved field, touching on almost every aspect of development. Handy, then, that Gojko Adzic has published a very comprehensive guide to the use of automated acceptance tests in contemporary Agile development practice, Bridging the Communication Gap: Specification by example and agile acceptance testing.

This book is a much-needed checkpoint in the on-going adventure to discover (and re-discover) how to write software effectively. Gojko is a very energetic enthusiast for these ideas, and a very experienced practitioner of them. His knowledge and expertise is present on every page.

A strong theme runs through the book—that the reason we capture examples of required behaviour and automate validation of them is to improve communication. Examples turn out to be a very powerful way to understand a problem domain and to explore a solution suitable for that domain. There turn out to be fascinating reasons for why this is true, but Gojko quite reasonably focusses on practical advice.

The main body of the book tells a story, a story of understanding, finding, and using examples to create shared understanding across a team. Gojko gives very concrete advice in a series of short chapters and explains how to do this. How to organise a workshop to find examples, how to find good examples, how to use tools to automate validation, how to use the resulting tests to guide development. Each chapter ends with a handy bullet list of key points. Together with other material on the best use for developers to make of such checked examples, and how to fit example discovery and capture into a typical Agile development process Bridging the Communication Gap provides as close to a vade mecum for newcomers to the discipline of functional test driven development as we are likely to see.

Gojko draws informative parallels with other techniques more or less strongly aligned with the Agile development world. This places the practice of Agile acceptance testing in context, and as a team-wide activity, reinforcing the cross-functional nature of the tool. Always the emphasis is on helping the various stakeholders in a development project communicate better.

There is a survey of tools available for this kind of work, which I might wish were slightly broader in scope and a little more detailed, but it does give a good overview of the market leaders. "Market leaders" in the weakest sense, since it turns out that the best tools for this kind of work are all FOSS: big-ticket corporate testing tools really aren't in this game.

Various points regarding writing and using tests are illustrated with (of course) illuminating examples. Also described are limitations of these techniques and some pitfalls to watch out for, something that more promoters of development techniques should provide.

The book is self-published and my copy was printed by Lightening Source. Books produced this way are getting better all the time, but are still not presented at the level of quality one would expect from a commercial publishing house. The pages seem very full and with the choice of font made the text a very dark colour which I don't find easy to read. The section and sub-section headings are sometimes over long and are not laid out well, a combination that I found made the book less easy to navigate than it might have been.

I will be using with book with clients and recommending it to them for future reference. A boon to the community.

Let over Lambda

Let over Lambda is a new self–published book on lisp by Doug Hoyte. I'm not quite sure what to make of it, overall.

It's great to see a book full of straight-ahead programming these days rather than mere system composition. It's especially great to see an extended work dealing with programming in the small. It's great fun to see someone who really likes programming as an activity in its own right exhibit their enjoyment. It's a great pleasure to see assembly language appear in a programming book of the 21st century. I find the curious combination of lisp being at once both a very high level language suited to symbolic programming and being very close to the metal most stimulating. That's a pair of properties that the programming language design mainstream seems to have abandoned. Java, for instance, doesn't feel particularly close even to the JVM.

It's especially great to see a lisp afficionado standing up for vi.

Assembler arises in a couple of spots where the impact of macros, the parsimony of lisp's internal representations and the intelligence of the lisp compiler combine to collapse quite sophisticated source code down to startlingly few opcodes. Which is all very fascinating. So much so that I was inspired to resurrect the SBCL installation on my Mac and go refresh my memory of how cute the disassemble function is. However, it feels to me as if an opportunity has been lost to take that just a bit further and come up with some Programming Perls–like startling observations about performance.

The book builds up to a very interesting exercise in implementing Forth. It's very nicely done and a great illustration of how easy it is to implement one interesting language given another. Lisp/Prolog used to be the canonical pair, I think. This illustration makes a good case for lisp/forth being roughly as illuminating.

Along the way there are several not–quite–consistant claims about what the book is for and the big build up to the alleged principle of “duality of syntax” is a very long run for a very short slide. Again, it feels as if an opportunity to do somehting really startling has been lost. There's a sort of plonking “here it is” presentation of this and other material. It's often good and interesting material, but needs a little bit more development in places.

It's perhaps not so great to have the, what shall I call it? unfettered enthusiasm of the author for lisp, macros and all that they imply coming at you un–moderated. I don't think that a commercial editor would have allowed quite so much polemic to make it onto the page. There's a bit too much direct quotation of Paul Graham material (“Blub”, “secret weapon”, you know the sort of stuff) that makes it quite clear that there are on the one hand people who get it, and on the other dullards. This is made very explicit on the back cover blurb:

Only the top percentile of programmers use lisp and if you can understand this book you are in the top percentile of lisp programmers.

Hmm. I have a strong feeling that I understand most of what's in the book and also that I'm not in the top of the top. Whatever that means. I'm not even a “lisp programmer” in any very serious sense of the term. Faced with a little light programming to do then in the absence of any other constraints I'm likely to reach for Scheme—and that brings me to another item that a commercial editor probably wouldn't have let through.

You might imagine that the differing trade–offs made in Scheme and Common Lisp are something that reasonable people could agree to disagree about. Hoyte wants his reader to understand very clearly that this is not so: the choices made in Scheme are wrong (emphasis in the original) and those made in CL are right (emphasis also in the original). The first one of these assertions was amusing enough. The second, not so much. And they just keep on coming. Hoyte is far too young to be settling scores from some X3J13 puch–up, wich would be embarrasing enough, so it all ends up looking a bit adolescent to me.

One last thing...at least in the print–on–demand form I've got from Lightning Source UK the book looks absolutely ghastly. “Made with lisp” says the front matter. Lisp with a lot of help from TeX and that's really not good enough for 2009, not without a lot more tuning than has gone into this. And Lightning Source (or whomever did the camera-ready copy) have originated the work at too low a resolution. That and the lazy choice of CMR combined with the glossy toner makes the actual print a less than comfortable read. Self–publishig has a long way to go yet.

Agile Adoption Patterns

I've just done a first pass through Amr Elssamadisy's cracking new book Agile Adoption Patterns. It's a timely work—enough teams have adopted enough Agile practices enough times that there should be patterns by now. And here they are.

There's a lot to like about the book. I especially appreciate the consistent message throughout that we do these practices because of their tie to business value. Not for truth and beauty, not for right versus wrong, but because they make our customers happy through the means of more money sooner, more often. There is an explicit mapping from various enhancements to business value onto clusters of the patterns. There is also mappings by business or process smell (of which there is a good, short catalogue presented). For each kind of business benefit the patterns within each cluster are logically related and given a partial order with respect to how well they help with that goal.

Separately, the clusters of patterns are described themselves as patterns, which is a nice organising principle. Agile Adoption Patterns is quite explicitly a handbook for finding out why your organisation might want to adopt Agile and then building a strategy to make that happen. A damn handy thing to have.

Scattered through the pattern catalogue there are little diagrams relating the patterns. I might wish for more of these. 

The patterns themselves contain a "Sketch" section, in which a surprisingly large cast of characters play out little vignettes. Dave Developer comes to realise the value of stand–up meetings because he sees Scott ScrumMaster [sic] removing his blockers, and so forth. I know that this style of thing is very fashionable these days, but it makes me cringe. Not only that, but I have a terrible memory for names, so keeping these fourteen characters lined up in my head is a strain.

The patterns have the usual "Therefore" section with the things–to–do in it, followed by and "Adoption" section telling you how to get there. They are all quite meaty, concrete and honest.  And best of all is the "But" section telling you common mis–steps, gotchas, misunderstandings and how to recognise same. This is outstanding! A common shorthand description of what a pattern is (in fact, it's in this book too) is words to the effect of a "solution to a problem in a context" Which is sort–of true a far as it goes but has its problems, mostly around the term ''solution". 

Oh, how we love "solutions" in the IT industry. A more accurate but less compelling description what patterns are is that they are mappings form one context to another, in which certain conflicting forces are more agreeably disposed (or resolved) in the latter than in the former. These "But" sections describe common scenarios (I've seen a lot of them, and so have you, I'll bet: Continuous Integration but continuously broken build, anyone?) that you could have and still make some sort of Jesuitical argument to be in agreement with the "Therefore", but actually are very wide of the mark. The next time I write any patterns, they will have a "But" section.

The highest level organisation of the patterns is into those concerned primarily with Feedback, technical practices, supporting practices and the cluster patterns. I was most interested to note that "Coach" is a supporting practice, but the role of ScrumMaster is assumed throughout.

I am one of the latter, but I'd rather be one of the former. Not so much of an option these days. Well, that's the power of marketing for you.

Meanwhile, one of the nicest things about having patterns is having a shared vocabulary. I think that Agile Adoption Patterns will become the standard reference for talking about Agile adoption, which will make my professional life easier and that of may others. A service to the community.

"Opportunities for Improvement"

The pattern form used is has nine sections and I'm not sure it helps to have each section shown in the table of contents. I feel the lack of a ready–to–hand one or two page list of all the patterns by name. Twelve pages of TOC for 320 pages of content seems a bit excessive. The same syndrome shows up in the index. If all the parts of a pattern are within a four page range do they really all need their own individual index entry? This is really a shame as the book otherwise benefits from the several other complementary ways to navigate it.

There is a stunningly egregious formatting botch on page 207. I'm sure this volume will go into multiple printings and I hope that someone at A–W gets that fixed.